KR20210102415A - Integrated aromatics separation process with selective hydrocracking and steam pyrolysis process - Google Patents

Abstract

The aromatics extraction and hydrocracking process is integrated with the steam pyrolysis unit to achieve better control of hydrocracking operating severity and/or catalytic reactor volume design requirements by separately treating the aromatics-rich and aromatics-lean fractions of the hydrocracking unit. Optimize performance.

Description

Integrated aromatics separation process with selective hydrocracking and steam pyrolysis process

The present invention relates to hydrocracking processes and systems, and more particularly to processes for the efficient reduction of catalyst-contaminating nitrogen-containing aromatics in hydrocarbon mixtures.

Hydrocracking unit operation is widely used in petroleum refineries to treat various feeds. The conventional hydrocracking unit process feed boils in the range of 370°C to 520°C, and the residual hydrocracking unit processes the feed above 520°C. In general, the hydrocracking process splits the molecules of the feed into smaller, ie lighter, molecules with higher average volatility and greater economic value. Additionally, hydrocracking typically improves the quality of hydrocarbon feedstocks by increasing the hydrogen-to-carbon ratio and by removing undesirable organic sulfur and organic nitrogen compounds. The significant economic benefits derived from hydrocracking operations have resulted in substantial process improvements and the development of improved catalysts with greater activity.

Conventional hydrocracking processes in the prior art require the entire feedstock to be subjected to the same hydrocracking reaction zone to accommodate feed components that require increased severity for conversion, or alternatively to achieve desirable process economics. This requires operating conditions at which the overall yield must be sacrificed.

Mild hydrocracking or single-stage hydrocracking operations, typically the simplest of known hydrocracking configurations, are more severe than typical hydrotreating processes and run at less severe operating conditions than typical high pressure hydrocracking. Single or multiple catalyst systems may be used depending on the nature and quality of the feedstock and product specifications. Multiple catalyst systems can be arranged in a stacked-bed configuration or in a series of reactors. Mild hydrocracking operations are generally more cost effective, but typically result in both lower yields and reduced quality of the middle distillation product compared to high pressure hydrocracking operations.

In a series-flow configuration, _{the entire hydrocracked product stream from the first reaction zone, comprising light gases such as C 1} -C ₄ , H ₂ S, NH ₃ , and all remaining hydrocarbons, is transferred to the second reaction zone. is sent to In a second stage configuration, the feedstock is purified through a hydrotreating catalyst bed in a first reaction zone. The effluent is passed to a fractionation zone column to separate boiling light gases, naphtha and diesel products in the temperature range of 36°C to 370°C. Heavier hydrocarbons boiling above 370° C. are then passed to a second reaction zone for further cracking.

In general, most hydrocracking processes practiced for the production of middle distillates and other valuable fractions retain aromatics having boiling points in the range of about 180°C to 370°C. Aromatics boiling above the middle distillate range are also present in the heavier fractions.

In all of the hydrocracking process configurations described above, the cracked products, along with partially cracked and unconverted hydrocarbons, are passed through a distillation column along with unconverted products that nominally boil above 370° C., respectively, between 36° C.-180° C. , boiling in the nominal range of 180°C-240°C and 240°C-370°C into products comprising naphtha, jet fuel/kerosene and diesel. Typical jet fuel/kerosene fractions, such as those having a smoke point >25 mm, and diesel fractions, eg, having a cetane number >52, are of high quality and well above worldwide transport fuel specifications. Although the hydrocracking unit products have relatively low aromaticity, any remaining aromatics lower the key indicator properties of smoke point and cetane number for these products.

The lower olefins, i.e., ethylene, propylene, butylene and butadiene, and aromatics, i.e., benzene, toluene and xylene, are basic intermediates widely used in the petrochemical and chemical industries. Thermal cracking or steam pyrolysis is a widely used process to obtain these compounds in the presence of steam and in the absence of oxygen. The feedstock for the steam pyrolysis reactor may include petroleum gas and distillates such as naphtha, kerosene and gas oil. Availability of these feedstocks is generally limited and requires expensive and energy intensive processes for their production at crude oil refineries.

Studies have been conducted using heavy hydrocarbons as feedstock for steam pyrolysis reactors. A major disadvantage of conventional heavy hydrocarbon pyrolysis operations is coke formation. For example, a steam pyrolysis process for heavy liquid hydrocarbons is disclosed in US Pat. No. 4,217,204, in which a mist of molten salt is introduced into a steam pyrolysis reaction zone to minimize coke formation. In one example using Arabian Light Crude with 3.1 wt % Conradson Carbon Residue (CCR), the cracking unit was able to continue operating for 624 hours in the presence of molten salt. In the comparative example where no molten salt was added, the steam pyrolysis reactor became clogged and inoperable after only 5 hours due to the formation of coke in the reactor.

Also, when heavy hydrocarbons are used as feedstocks for steam pyrolysis reactors, the yield and distribution of olefins and aromatics are different from those using light hydrocarbon feedstocks. Heavy hydrocarbons have a higher aromatics content than light hydrocarbons, which is expressed as a higher Bureau of Mines Correlation Index (BMCI), which is a measure of the aromaticity of the feedstock calculated as follows.

BMCI=87552/VAPB+473.5*(SG)-456.8 (One)

where: VAPB = the volume average boiling point in Rankine temperature, and SG = the specific gravity of the feedstock.

As the BMCI decreases, the ethylene yield is expected to increase. Thus, in order to obtain higher yields of the desired olefins, and to avoid undesirable product and coke formation in the reactor coil section, a high paraffinic or low aromatics feed is generally preferred for steam pyrolysis.

Systems and methods for subjecting a hydrocarbon feed to the initial stage of aromatics extraction and treating the aromatics-rich and aromatic-lean fractions separately and under different hydrocracking conditions are described in USP 9,144,752, USP 9144,753, USP 9,145,521 and 9,556,388, the disclosures of which are incorporated herein by reference. The systems and reaction schemes relate to catalytic hydroprocessing reactions in multiple stages and, in some cases, multiple reaction vessels having first or second stages.

The problem addressed by the present disclosure is to provide an improved process and system for hydrocracking heavy hydrocarbon feedstocks to produce cost effective and efficient clean transport fuels and light olefins.

A further problem to be addressed is to optimize the design and operation of the hydrocracking unit, thereby reducing the severity of operating conditions, and reducing the catalytic reactor volume requirements for comparable product quality and output.

This problem is solved and additional advantages are realized by the process of the present disclosure in which the hydrocracking unit feed is separated into fractions containing different classes of compounds having different reactivity under the respective hydrocracking conditions to which they are applied.

As used in the following description and claims, the term "hydrogen-rich" fraction refers to the fraction recovered from the aromatic separation process of a heavy hydrocarbon feed containing a majority of the paraffinic and olefinic compounds present in the initial feed, and the term A “hydrogen-lean” fraction will be understood to refer to a fraction recovered from an aromatics separation process containing a majority of the aromatics present in the initial feed.

Embodiment 1 - Selective single-stage hydrocracking system and method

According to an embodiment, the present disclosure broadly encompasses an integrated hydrocracking process comprising a steam pyrolysis reactor for treating a heavy hydrocarbon feedstream containing aromatics, paraffins and olefinic compounds, which comprises a majority of the aromatics in the feed. separating and hydrocracking a hydrogen-lean fraction of the initial feed, and separately treating the remaining hydrogen-rich fraction containing a majority of the non-aromatic compounds in the initial feed.

As described in more detail below, the single-stage once-through hydrocracker configuration includes an integrated aromatics separation unit in which the feedstock is separated into a hydrogen-lean fraction and a hydrogen-rich fraction; The hydrogen-lean fraction is passed to a hydrocracking reaction zone operating under conditions effective to hydrotreat and/or hydrocrack at least a portion of the aromatic compounds contained in the hydrogen-lean fraction to produce a hydrocracking reaction zone effluent. become; The hydrogen-rich fraction is subjected to a steam pyrolysis reaction zone operating under conditions effective to crack at least a portion of the paraffinic and naphthenic compounds present in the hydrogen-rich fraction to produce an effluent containing light olefins, gases and pyrolysis oils. passed; and the hydrocracking reaction zone effluent and the second stream pyrolysis hydrocracking reaction zone effluent are combined and fractionated to produce at least one product stream and at least one bottom stream.

Since aromatics extraction operations typically do not provide a sharp cut-off between aromatics and non-aromatics, the hydrogen-rich fraction contains a majority of the non-aromatics content of the initial feed and a small fraction of the aromatics content of the initial feed, and hydrogen- The lean fraction contains most of the aromatic content of the initial feed and a small portion of the non-aromatic content of the initial feed. As will be apparent to those skilled in the art, the respective proportions of non-aromatics in the hydrogen-lean fraction and the amount of aromatics in the hydrogen-rich fraction are applicable to the type of extraction process used, the theoretical number of extractors (the type of extraction used). ), depending on a variety of factors, including the type of solvent and the solvent ratio.

The feed portion extracted as a hydrogen-lean fraction includes aromatic compounds containing heteroatoms and those without heteroatoms. Aromatic compounds containing heteroatoms extracted and recovered as part of the hydrogen-lean fraction include aromatic nitrogen compounds such as pyrrole, quinoline, acridine, carbazole and derivatives thereof, and thiophene, benzothiophene and derivatives thereof, and aromatic sulfur compounds such as dibenzothiophene and derivatives thereof. These nitrogen-containing and sulfur-containing aromatics are generally targeted in the aromatic separation step(s) by their solubility in the extraction solvent. In certain embodiments, the removal of nitrogen-containing and sulfur-containing aromatics is enhanced by the use of additional steps and/or optional sorbents. Various non-aromatic sulfur-containing compounds that may be present in the initial feed, ie prior to hydrotreating, include mercaptans, sulfides and disulfides. In a preferred embodiment, the aromatic extraction process and operating conditions are selected to minimize the amount of non-aromatic nitrogen- and sulfur-containing compounds passed through the hydrogen-lean fraction.

As used herein, the term "most of the non-aromatics" means greater than at least 50% by weight (W%) of the non-aromatics content of the feed to the extraction zone, in certain embodiments greater than about 85 W%, and in other embodiments at least greater than about 95 W %. Also, as used herein, the term “minor fraction of non-aromatics” refers to no more than 50 W% of the non-aromatic content of the feed to the extraction zone, in certain embodiments no more than about 15 W%, and in other embodiments no more than about 15 W%. It means less than about 5 W% in.

Also, as used herein, the term “most of the aromatics” means greater than at least 50 W% of the aromatic content of the feed to the extraction zone, in certain embodiments greater than at least about 85 W%, and in other embodiments at least about 95 W%. means exceeding W%. Also, as used herein, the term “minor fraction of aromatics” refers to no more than 50 W% of the aromatic content of the feed to the extraction zone, in certain embodiments no more than about 15 W%, and in other embodiments no more than about 5 W % or less.

Embodiment 2 - Selective series-flow hydrocracking system and method for producing distillate and light dil olefins

According to one or more embodiments, the present invention relates to systems and methods for combining conventional hydrocracking and steam pyrolysis of a heavy hydrocarbon feedstock to produce clean transport fuels and light olefins. The integrated hydrocracking process comprises hydrocracking a hydrogen-lean fraction of an initial feed, and separately steam cracking a hydrogen-rich fraction.

The series-flow hydrocracker configuration, described in more detail below, includes an integrated aromatics separation unit in which the feedstock is separated into a hydrogen-lean fraction and a hydrogen-rich fraction; The hydrogen-lean fraction is a first stage hydrogenation operating under conditions effective to hydrotreat and/or hydrocrack at least a portion of the aromatic compounds contained in the hydrogen-lean fraction and produce a first stage hydrocracking reaction zone effluent. passed to the decomposition reaction zone; the hydrogen-rich fraction is passed to a steam pyrolysis reaction zone operating under conditions effective to crack at least a portion of the paraffin and naphthenic compounds contained in the hydrogen-rich fraction, and to produce a steam pyrolysis reaction zone effluent; the first stage hydrocracking reaction zone effluent is passed to a second stage hydrocracking reaction zone to produce a second stage hydrocracking reaction zone effluent; and the steam pyrolysis reaction zone effluent is fractionated in a fractionation zone to produce a product stream and a bottom stream that are separately recovered.

Embodiment 3 - Selective hydrocracking system and method for producing distillate and light olefins

According to embodiments, the present disclosure broadly encompasses methods of hydrocracking heavy hydrocarbon feedstocks to produce clean transportation fuels. The integrated aromatics separation, hydrocracking and steam pyrolysis process involves hydrocracking the hydrogen-lean fraction of the initial feed separately from the hydrogen-rich fraction.

The series-flow hydrocracker, described in more detail below, comprises an integrated aromatics separation unit in which the feedstock is separated into a hydrogen-lean fraction and a hydrogen-rich fraction; The hydrogen-lean fraction is a first stage hydrogenation operating under conditions effective to hydrotreat and/or hydrocrack at least a portion of the aromatic compounds contained in the hydrogen-lean fraction and produce a first stage hydrocracking reaction zone effluent. passed to the decomposition reaction zone; a mixture of the first stage hydrocracking reaction zone effluent and the hydrogen-rich fraction after gas-liquid separation is passed to a steam pyrolysis reaction zone to produce a combined steam cracked hydrocarbon pyrolysis reaction zone effluent; and the steam cracked hydrocarbon pyrolysis reaction zone effluent is fractionated in a fractionation zone to produce a product stream and a bottom stream that are separately recovered.

Embodiment 4 - Selective two-stage hydrocracking system and method to produce distillate and light olefins

According to an embodiment, the present invention relates to a system and method for hydrocracking and steam pyrolysis of heavy hydrocarbon feedstocks to produce clean transport fuels and light olefins. The integrated hydrocracking process comprises hydrocracking the hydrogen-lean fraction of the initial feed separately from the hydrogen-rich fraction.

The two-stage hydrocracker configuration, described in more detail below, includes an integrated aromatics separation unit in which the feedstock is separated into a hydrogen-lean fraction and a hydrogen-rich fraction; The hydrogen-lean fraction is a first stage hydrocracking operating under conditions effective to hydrotreat and/or hydrocrack at least a portion of the aromatic compounds present in the hydrogen-lean fraction, and to produce a first stage hydrocracking reaction zone effluent. passed to the first vessel of the reaction zone; the hydrogen-rich fraction is passed to a steam pyrolysis reaction zone operating under conditions effective to crack at least a portion of the paraffinic and naphthenic compounds contained in the hydrogen-rich fraction to produce a steam cracked reaction zone effluent; a mixture of the first vessel first stage hydrocracking reaction zone effluent and the grime pyrolysis reaction zone effluent is fractionated in a fractionation zone to produce a product stream and a bottom stream; at least a portion of the fractionation zone bottom stream is passed to a second stage hydrocracking reaction zone to produce a second stage hydrocracking reaction zone effluent; and the second stage hydrocracking reaction zone effluent is passed to a fractionation zone.

Embodiment 5 - Selective two-stage hydrocracking system and method for producing distillate and light olefins

According to embodiments, the present disclosure broadly understands methods for hydrocracking and steam pyrolysis of heavy hydrocarbon feedstocks to produce clean transport fuels and light olefins. The integrated hydrocracking process comprises hydrocracking the hydrogen-lean fraction of the initial feed separately from the hydrogen-rich fraction.

The two-stage hydrocracker configuration, described in greater detail below, includes an integrated aromatics separation unit in which the feedstock is separated into a hydrogen-lean fraction and a hydrogen-rich fraction; The hydrogen-lean fraction is a first stage hydrogenation operating under conditions effective to hydrotreat and/or hydrocrack at least a portion of the aromatic compounds contained in the hydrogen-lean fraction and produce a first stage hydrocracking reaction zone effluent. passed to the decomposition reaction zone; the first stage hydrocracking reaction zone effluent is separated to produce a product stream and a bottom stream, wherein at least a portion of the bottom stream is mixed with a hydrogen-rich fraction; and the mixture is passed to a steam pyrolysis reaction zone to produce a steam cracked reaction zone effluent, which is passed to a fractionation zone for product separation and recovery.

In another aspect, embodiments and advantages of these exemplary processes are detailed below. Moreover, it will be understood that both the foregoing background and the following detailed description are intended to set forth various aspects and embodiments, and to provide an overview or framework for understanding the nature and characteristics of the broad aspects and embodiments of the process. The accompanying drawings illustrate various aspects and process embodiments by way of example and facilitate understanding. The drawings, together with the rest of the specification, serve to explain the principle and practice of the process.

Embodiments of processes and systems and apparatus for carrying out the present disclosure will be described in greater detail below with reference to the accompanying drawings in which the same or similar components are referred to by like numbers.
1 is a simplified schematic flow diagram of an embodiment of a single stage hydrocracking system suitable for practicing the process of the present disclosure.
2 is a simplified schematic flow diagram of an embodiment of a selective series-flow hydrocracking system suitable for practicing the process of the present disclosure.
3 is a simplified schematic flow diagram of an embodiment of a selective hydrocracking system suitable for practicing the process of the present disclosure.
4 is a simplified schematic flow diagram of an embodiment of an optional two-stage hydrocracking system suitable for practicing the process of the present disclosure.
5 is a simplified schematic flow diagram of another embodiment of an optional two-stage hydrocracking system suitable for practicing the process of the present disclosure.

Referring to the schematic illustration of FIG. 1 , a process flow diagram of an integrated hydrocracking unit and system 100 in the configuration of a single-stage hydrocracking unit apparatus and system is shown. Apparatus 100 includes an aromatics extraction zone 140 , a hydrocracking reaction zone containing a hydrocracking catalyst 150 , a steam pyrolysis reaction zone 160 , and a fractionation zone 170 .

The aromatics extraction zone 140 includes at least a hydrocarbon feed inlet 102 , a hydrogen-lean flow outlet 104 and a hydrogen-rich stream outlet 106 . In certain embodiments, the feed inlet 102 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 120 to receive all or a portion of the fractionator bottom 174 . The various embodiments and/or unit-operations used in the aromatics separation zone 140 are used in accordance with the prior art based on the nature of the aromatics present in the initial feed.

The hydrocracking reaction zone 150 includes an inlet 151 in fluid communication with a hydrogen-lean stream outlet 104 , a source of hydrogen gas received via conduit 152 , and a hydrocracking reaction zone effluent outlet 154 . . In certain embodiments, the inlet 151 is an optional recirculation conduit 156 to receive all or a portion of the fractionator bottom 174, with flow controlled by the three-way valve 157. in fluid communication with fractionation section 170 via

The hydrocracking reaction zone 150 is generally operated under harsh conditions to treat the hydrogen-lean stream. As used herein, it is to be understood that the term “severe conditions” is relative and that the range of operating conditions depends on the particular composition of the feedstock being treated. In certain embodiments, these conditions include a reaction temperature ranging from about 300°C to 500°C, and in certain embodiments from about 380°C to 450°C; a reaction pressure ranging from about 100 bar to 200 bar, and in certain embodiments from about 130 bar to 180 bar; a hydrogen feed rate of up to about 2500 standard liters per liter of hydrocarbon feed (SLt/Lt), in certain embodiments from about 500 to 2500 SLt/Lt, and in further embodiments from about 1000 to 1500 SLt/Lt; and feed rates ranging from about 0.25 h ⁻¹ to 3.0 ⁻¹ , and in certain embodiments from about 0.5 ⁻¹ to 1.0 ^{−1 .}

The catalyst used in hydrocracking reaction zone 150 has one or more active metal components selected from IUPAC groups 6-10 of the Periodic Table of Elements. In certain embodiments, the active metal component is one or more of cobalt, nickel, tungsten and molybdenum, and is typically deposited or otherwise incorporated onto a support such as alumina, silica-alumina, silica, or zeolite.

Steam pyrolysis reaction zone 160 includes a hydrogen-rich stream outlet 106 and an inlet 161 in fluid communication with a source of steam via conduit 162 , and a steam pyrolysis reaction zone effluent outlet 164 . In certain embodiments, the inlet 161 is connected to the fractionation section 170 via an optional recirculation conduit 166 to receive all or a portion of the bottom 174, with flow controlled by the three-way valve 167. ) in fluid communication with

Steam pyrolysis reaction zone 160 has a wide temperature range of 400° C. to 900° C., but a preferred operating range is 800° C. to 900° C. in the convection section and in the pyrolysis section; a pressure in the convection section in the range from 1 bar to 3 bar, and a pressure in the pyrolysis section in the range from 1 bar to 3 bar; steam-to-hydrocarbon ratio in the convection section ranging from 0.3:1 to 2:1; and residence times in the convection section and in the pyrolysis section ranging from 0.05 seconds to 2 seconds.

Fractionation zone 170 includes an inlet 171 in fluid communication with a hydrocracking reaction zone effluent outlet 154 and a steam pyrolysis reaction zone effluent outlet 164 . Fractionation zone 170 also includes a product stream outlet 172 and a bottom stream outlet 174 . While one product outlet is shown for simplicity, it should be understood by those skilled in the art that multiple product fractions can and are generally recovered from fractionation zone 170 . Also, while one fractionation zone 170 is shown in fluid communication with both effluents 154 and 164 from the respective hydrocracking and steam pyrolysis reaction zones 150, 160, in certain embodiments separate fractionation Zones (not shown) may be used to meet the required specifications for the product contained in one or both of the effluent streams 154 and 164 .

The hydrocarbon feedstock is introduced via inlet 102 into aromatic extraction zone 140 for extraction of hydrogen-lean fraction 106 and hydrogen-rich fraction 104 . Optionally, feedstock 102 is combined with all or part of bottom 174 from fractionation zone 170 via recirculation conduit 120 , the flow being controlled by a three-way valve.

The hydrogen-lean fraction 104 generally comprises a majority of the aromatic nitrogen-containing and sulfur-containing compounds initially present in the feedstock and a small fraction of the non-aromatic compounds initially present in the feedstock. Aromatic nitrogen-containing compounds extracted with the hydrogen-lean fraction include pyrrole, quinoline, acridine, carbazole and derivatives thereof. Aromatic sulfur-containing compounds which are extracted and constitute part of the hydrogen-lean fraction include thiophene, benzothiophene and its long-chain alkylated derivatives, dibenzothiophene and its alkyls such as 4,6-dimethyl-dibenzothiophene. derivatives. The hydrogen-rich fraction generally comprises a majority of the non-aromatic compounds initially present in the feedstock and a small proportion of the aromatic nitrogen- and sulfur-containing compounds initially present in the feedstock. The hydrogen-rich fraction is substantially free of refractory nitrogen-containing compounds, and when the extraction process is operating optimally, the hydrogen-lean fraction comprises nitrogen-containing aromatic compounds.

The hydrogen-lean fraction discharged through outlet 104 is passed to inlet 151 of hydrocracking reaction zone 150 and mixed with hydrogen gas introduced through conduit 152 . Optionally, the hydrogen-lean fraction is combined with all or part of the bottom 174 from fractionation zone 170 via recirculation conduit 156 with flow controlled by 3-way valve 157 . The compounds contained in the hydrogen-lean fraction comprising aromatic compounds are hydrotreated and/or hydrocracked. The hydrocracking reaction zone 150 is operated under relatively harsh conditions. In certain embodiments, these relatively harsh operating conditions of hydrocracking reaction zone 150 are more severe than previously known harsh hydrocracking conditions due to the relatively higher concentrations of aromatic nitrogen- and sulfur-containing compounds. According to an advantage for the present disclosure, the capital and operating costs of these more severe conditions are reduced in the hydrocracking reaction zone 150 as compared to the full range feed to be processed in a conventional harsh hydrocracking unit operation of the prior art. This is offset by the reduced volume of the hydrogen-lean feed. The resulting advantages also include improved production rates of the desired product.

The hydrogen-rich fraction discharged through outlet 106 is passed to inlet 161 of steam pyrolysis reaction zone 160 and mixed with steam introduced through conduit 162 . Optionally, the hydrogen-rich fraction is combined with all or a portion of the bottom 174 from the fractionation zone 170 via a recirculation conduit 166 , the flow being controlled by a three-way valve 167 . The compounds contained in the hydrogen-rich fraction comprising paraffins and naphthenes are steam cracked. Steam pyrolysis reaction zone 160 is operated under the conditions described above.

The hydrocracking reaction zone, steam, thermal cracking zone the effluent is at least one intermediate separator vessel for removing the gas containing the excess H _2, H ₂ S, NH _3, methane, ethane, ethylene, propane, propylene, butane and butylene ( sent to the city). The liquid effluent is directed to a fractionation section 170 for recovery of the liquid product via outlet 172 which may include naphtha boiling nominally in the range of about 36°C to 180°C and diesel boiling nominally in the range of about 180°C to 370°C. ) through the inlet 171. The bottom stream exiting through outlet 174 comprises unconverted hydrocarbons and/or partially cracked hydrocarbons, which may include those having a boiling point greater than about 370°C. It should be understood that the product cut points between fractions are representative only, and in practice the cut points are selected based on design characteristics and known considerations for a particular feedstock. For example, the value of the cut point can vary up to about 30° C. in the described embodiments. It is also understood that although the integrated system is shown and described as one fractionation zone 170, in certain embodiments, a separate fractionation zone may be operated with better temperature control to enhance recovery of certain products. should be

All or part of the bottom may be purged through conduit 175, for example, for processing in other unit operations or refineries. In certain embodiments, to maximize yield and conversion of the initial hydrocarbon feed to the system, a portion of bottom 174 is optionally separated from aromatic separation unit 140, hydrocracking reaction zone 150 and/or steam pyrolysis reaction zone ( 160), as indicated by dashed lines 120, 156 and 166, respectively.

Example

Example 1

A sample of vacuum gas oil (VGO) derived from Arab light crude oil was solvent extracted in an extractor at 60° C. and atmospheric pressure using furfural in a solvent to oil ratio of 1.1:1.0 to obtain a hydrogen-lean fraction and a hydrogen-rich fraction produce The hydrogen-rich fraction yield was 52.7 W% and contained 0.43 W% sulfur and 5 W% aromatics. The hydrogen-lean fraction yield was 47.3 W%, containing 95 W% aromatics and 2.3 W% sulfur. The properties of VGO, hydrogen-lean fractions and hydrogen-rich fractions are reported in Table 1.

characteristic VGO VGO
aromatic-rich VGO
Aromatic - Lean Density at 15°C kg/L 0.922 1.020 0.835 Tasso W% 85.27 Hydrogen W% 12.05 sulfur W% 2.7 2.30 0.43 nitrogen ppmw 615 584 31 MCR W% 0.13 aromatic W% 47.3 44.9 2.4 N + P W% 52.7 2.6 50.1

The hydrogen-lean fraction is a fixed bed hydrotreating unit containing Ni-Mo on amorphous silica-alumina catalyst at 150 Kg/cm hydrogen partial pressure, 400° C., liquid hourly space velocity of 1.0/hr and hydrogen feed rate of 1,000 SLt/Lt. was hydrotreated in A Ni-Mo catalyst was used to denitrify the hydrogen-lean fraction containing a significant amount of nitrogen content present in the original feedstock. The effluent is sent to a fractionator.

The hydrogen-rich fraction was subjected to steam pyrolysis for 0.35 seconds at 800° C., 1 bar, and a steam-to-hydrocarbon weight ratio of 0.6. The effluent from the hydrocracking and steam pyrolysis unit is sent to one or more separator vessels to degas and the liquid effluent is passed to a fecal section to recover the liquid product. The hydrogen lean stream and bottom from both units can be recycled, for example, to a steam pyrolysis unit to maximize yield.

The respective product yields resulting from the integrated hydrocracking and steam pyrolysis operations are reported in Table 2.

Hydrocracking, W% Steam Pyrolysis, W% W% characteristic VGO - rich in aromatics VGO - aromatic lean all stream # 154 164 171 Hydrogen 2.39 0.8 1.55 H ₂ S 2.42 0 1.14 NH ₃ 0.07 0 0.03 ethylene 20.5 10.80 propylene 14.0 7.38 butadiene 5.3 2.79 C ₁ -C ₄ 2.78 15.1 9.27 naphtha 19.08 19.3 19.20 middle distillate 38.04 0 18.00 unconverted bottom 40.00 25.00 32.10 gun 102.39 100 101.13 transform 60.00 75.00 67.90

Referring now to FIG. 2 , an aromatic extraction zone 140 comprising a first vessel of a first stage hydrocracking reaction zone 150 containing a first stage hydrocracking catalyst, a second stage containing the hydrocracking catalyst of an integrated hydrocracking apparatus and system 200 in the configuration of a series-flow hydrocracking unit comprising a second vessel 180 of a one-stage hydrocracking reaction zone, a steam pyrolysis reaction zone 160, and a fractionation zone 170; A process flow diagram appears.

Aromatics extraction zone 140 includes a feed inlet 102 , a hydrogen-lean stream outlet 104 , and a hydrogen-rich stream outlet 106 . In certain embodiments, the feed inlet 102 is in fluid communication with the fecal section 170 via an optional recirculation conduit 120 to direct all or a portion of the bottom 174 into a flow controlled by one or more three-way valves. Accept.

As shown, first vessel 150 includes a hydrogen-lean stream outlet 104 and an inlet 151 in fluid communication with a source of hydrogen gas introduced via conduit 152 . The first vessel 150 of the second stage hydrocracking reaction zone also includes a first vessel first stage hydrocracking reaction zone outlet 154 . In certain embodiments, inlet 151 is flow controlled by three-way valves 157 , 167 and 177 , respectively, via optional recirculation conduit 156 to receive all or part of bottom 174 . It is in fluid communication with the fractionation zone 170 .

The first vessel 150 of the first stage hydrocracking reaction zone is operated under harsh conditions. As used herein, "severe conditions" are to be understood as relative and the range of operating conditions is dependent on the feedstock being treated. In certain embodiments of the process described with reference to FIG. 2 , these conditions include a reaction temperature in the range of about 300° C. to 500° C., and in certain embodiments about 380° C. to 450° C.; a reaction pressure in the range of from about 100 bar to 200 bar, in certain embodiments from about 130 bar to 180 bar; a hydrogen feed rate of up to about 2,500 standard liters per liter of hydrocarbon feed (SLt/Lt), in certain embodiments from about 500 to 2,500 SLt/Lt, and in further embodiments from about 1,000 to 1,500 SLt/Lt; and a feed rate ranging from about 0.25 h ⁻¹ to 3.0 h ⁻¹ , and in certain embodiments from about 0.5 h ⁻¹ to 1.0 h ^{−1 .}

The catalyst used in the first vessel of the first stage hydrocracking reaction zone has at least one active metal component selected from IUPAC groups 6-10 of the Periodic Table of Elements. In certain embodiments, the active metal component is one or more of cobalt, nickel, tungsten and molybdenum, which may be deposited or otherwise incorporated on a support such as alumina, silica-alumina, silica or zeolite.

The steam pyrolysis reaction zone includes a vessel 160 having a hydrogen-rich stream outlet 106 and an inlet 161 in fluid communication with a source of steam introduced via conduit 162 . The vessel 160 of the steam pyrolysis reaction zone also includes a steam pyrolysis reaction zone effluent outlet 164 .

The steam pyrolysis reaction zone 160 has a wide range of temperatures from 400° C. to 900° C., but the preferred operating range is from 800° C. to 900° C. in the convection section and in the pyrolysis section; a pressure in the convection section in the range from 1 bar to 3 bar and a pressure in the pyrolysis section in the range from 1 bar to 3 bar; steam-to-hydrocarbon ratio in the convection section ranging from 0.3:1 to 2:1; and residence times in the convection section and in the pyrolysis section ranging from 0.05 seconds to 2 seconds.

The second hydrocracking reaction zone 180 includes an inlet 181 in fluid communication with the first vessel first stage hydrocracking reaction zone effluent outlet 154 . In certain embodiments, the inlet 181 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 166 to receive all or a portion of the bottom 174 .

The second vessel 180 of the second stage hydrocracking reaction zone has a reaction temperature in the range of about 300° C. to 500° C., and in certain embodiments, about 330° C. to 420° C.; a reactor pressure ranging from about 30 bar to 130 bar, in certain embodiments from about 60 bar to 100 bar; a hydrogen feed rate of less than 2,500 SLt/Lt, in certain embodiments from about 500 to 2,500 SLt/Lt, and in further embodiments from about 1,000 to 1,500 SLt/Lt; and feed rates ranging from about 1.0 h ^-¹ to 5.0 h ^-¹ , in certain embodiments from about 2.0 h ^-¹ to 3.0 h ^-¹.

The catalyst used in the second hydrocracking reaction zone has at least one active metal component selected from IUPAC Groups 6-10 of the Periodic Table of the Elements. In certain embodiments, the active metal component is one or more of cobalt, nickel, tungsten, and molybdenum, which may be deposited or otherwise incorporated on a support such as alumina, silica-alumina, silica, or zeolite.

Fractionation zone 170 includes an inlet 171 in fluid communication with a steam pyrolysis reaction zone effluent 164 and a second hydrocracking reaction zone outlet 184 , a product stream outlet 172 and a bottom stream outlet 174 . do. It is noted that, although one product outlet is shown in this simplified schematic of the system, a number of product fractions will in fact be advantageously withdrawn from fractionation zone 170 .

The hydrocarbon feedstock is introduced via inlet 102 of aromatic extraction zone 140 for extraction of hydrogen-lean fractions and hydrogen-rich fractions. Optionally, the feedstock may be combined with all or a portion of the bottom 174 from the fractionation zone 170 through a recirculation conduit 120 along a passage through each of the three-way valves 177, 167, 157. have.

The hydrogen-lean fraction generally comprises a majority of the aromatic nitrogen- and sulfur-containing compounds initially present in the feedstock and a small fraction of the non-aromatic compounds initially present in the feedstock. Aromatic nitrogen-containing compounds extracted with the hydrogen-lean fraction include pyrrole, quinoline, acridine, carbazole and derivatives thereof. Aromatic sulfur-containing compounds extracted with the hydrogen-lean fraction include thiophene, benzothiophene and long chain alkylated derivatives thereof, and alkyl derivatives thereof such as dibenzothiophene and 4,6-dimethyl-dibenzothiophene. . The hydrogen-rich fraction generally comprises a majority of the non-aromatic compounds present in the initial feedstock and a small proportion of the aromatic nitrogen- and sulfur-containing compounds present in the initial feedstock. The hydrogen-rich fraction contains few refractory nitrogen-containing compounds and the hydrogen-lean fraction contains nitrogen-containing aromatic compounds.

The hydrogen-lean fraction withdrawn through outlet 104 passes through inlet 151 of first vessel 150 of first stage hydrocracking reaction zone and is mixed with hydrogen gas introduced through conduit 152 . Optionally, the hydrogen-lean fraction is combined with all or part of the bottom 174 from fractionation zone 170 via recycle conduit 156 . Compounds contained in the hydrogen-lean fraction comprising aromatic compounds are hydrotreated and/or hydrocracked. The first vessel 150 of the first stage hydrocracking reaction zone is operated under relatively harsh conditions. In certain embodiments, these relatively harsh operating conditions of the first vessel 150 are more severe than previously known harsh hydrocracking conditions due to the relatively higher concentrations of aromatic nitrogen- and sulfur-containing compounds. According to the advantages of the disclosed process, the capital and operating costs of these harsher conditions are reduced in volume of the hydrogen-lean feed processed in the first vessel 150 as compared to commonly known harsh hydrocracking unit operations in the prior art. is offset by

The hydrogen-rich fraction discharged through the outlet 106 is passed to the inlet 161 of the steam pyrolysis vessel 160 and mixed with the hydrogen gas introduced through the conduit 162 . Compounds contained in the hydrogen-rich fraction, including paraffins and naphthenes, are steam cracked.

The first stage hydrocracking reaction zone effluent exiting via outlet 154 is passed to inlet 181 of second stage hydrocracking reaction zone 180 . Compounds contained in the mixture of the first stage hydrocracking reaction zone effluent are combined with hydrogen gas via inlet 182 and subjected to hydrotreating and/or hydrocracking. In an embodiment, the free or dissolved hydrogen content in the first stage hydrocracker effluent is monitored in real time, and the hydrogen source pressure/flow to reaction zone 180 via inlet 182 is further If there is no or reduced requirement for hydrogen, eg, hydrogen provided via conduit 152 and passing unreacted to second stage hydrocracking reaction zone 180 , it may be reduced.

The second vessel 180 of the second stage hydrocracking zone operates under relatively mild cracking conditions, which may be milder than previously known mild hydrocracking conditions because of the relatively lower concentrations of aromatic nitrogen- and sulfur-containing compounds. As a result, capital and operating costs are reduced.

The second stage hydrocracking reaction zone effluent is more than one intermediate separator vessel for removing a gas containing an excess of H _2, H ₂ S, NH _3, methane, ethane, ethylene, propane, propylene, butane and butylene ( not shown). The liquid effluent, via outlet 172, is for recovery of a liquid product comprising, for example, naphtha boiling in a nominal range of about 36°C to 180°C and diesel boiling in a nominal range of about 180°C to 370°C. It is passed to the inlet 171 of the fractionation section 170 for the hazard. In practice, the compound will be withdrawn through a separate outlet, shown here for simplicity, as a single outlet 172 . The bottom stream exiting through outlet 174 comprises unconverted hydrocarbons and/or partially cracked hydrocarbons having, for example, a boiling point greater than about 370° C. It should be understood that the product cut points between fractions are representative only, and in practice the cut points are selected based on design characteristics and specific feedstocks. For example, the value of the cut point can vary up to about 30° C. in the described embodiments. Also, although the integrated system is shown and described as one fractionation zone 170, in certain embodiments a separate fractionation zone may be used to provide better temperature and separation control for recovery of specific fractions required to meet specific product specifications. It should be understood as being able to provide

All or a portion of the bottoms from fractionation zone 170 may be purged via conduit 175, for example, for processing in other unit operations or refineries. In certain embodiments, to maximize yield and conversion, a portion of bottom 174 is, as described above, each with flow(s) controlled by one or more three-way valves 157 , 167 and 177 , respectively. As indicated by dashed lines 120 , 156 and 186 , it is recycled to the aromatic separation unit 140 , the first vessel 150 of the first stage hydrocracking reaction zone and/or to the steam pyrolysis reaction zone 160 .

Referring now to FIG. 3 , a process flow diagram for an aromatic separation, hydrocracking and steam pyrolysis apparatus and system 300 integrated in the configuration of a hydrocracking unit apparatus is provided. System 300 includes an aromatics extraction zone 140 , a hydrocracking reaction zone containing a first stage hydrocracking catalyst 150 , a steam pyrolysis reaction zone 160 , and a fractionation zone 170 .

Aromatics extraction zone 140 includes a feed inlet 102 , a hydrogen-lean stream outlet 104 , and a hydrogen-rich stream outlet 106 . As will be described in more detail below, in certain embodiments, the feed inlet 102 is configured to receive all or a portion of the bottom 174, with flow controlled by the three-way valves 177, 167 and 157. It is in fluid communication with the downstream fractionation zone 170 via an optional recirculation conduit 120 for The unit-operations and/or various embodiments contained within aromatic separation zone 140 are constructed and operated to achieve maximum efficiency for the particular feedstock(s) being processed in accordance with principles and practices known in the art.

Hydrocracking reaction zone 150 includes a hydrogen-lean stream outlet 104 and an inlet 151 in fluid communication with a source of hydrogen gas introduced via conduit 152 . The first stage hydrocracking reaction zone 150 also includes a hydrocracking reaction zone outlet 154 . In certain embodiments, the inlet 151 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 156 to receive all or a portion of the bottom 174 .

The hydrocracking reaction zone 150 is operated under harsh conditions. As used herein, the term “severe conditions” is relative and the range of operating conditions depends on the feedstock being treated. For example, these conditions may include a reaction temperature ranging from about 300°C to 500°C, and in certain embodiments from about 380°C to 450°C; a reaction pressure ranging from about 100 bar to 200 bar, and in certain embodiments from about 130 bar to 180 bar; a hydrogen feed rate of less than about 2500 standard liters per liter of hydrocarbon feed (SLt/Lt), in certain embodiments from about 500 to 2500 SLt/Lt, and in further embodiments from about 1000 to 1500 SLt/Lt; and feed rates ranging from about 0.25 h ⁻¹ to 3.0 ⁻¹ , and in certain embodiments from about 0.5 ⁻¹ to 1.0 ^{−1 .}

The catalyst used in the hydrocracking reaction zone has at least one active metal component selected from IUPAC groups 6-10 of the Periodic Table of the Elements. In certain embodiments, the active metal component is one or more of cobalt, nickel, tungsten and molybdenum that is typically deposited or otherwise incorporated on a support such as alumina, silica-alumina, silica or zeolite.

Steam pyrolysis reaction zone 160 includes a hydrogen-rich stream outlet 106 , a first stage hydrocracking reaction zone liquid outlet outlet 154 after gas-liquid separation (not shown), and steam introduced via conduit 162 . an inlet 161 in fluid communication with the steam pyrolysis reaction zone outlet 164 . In certain embodiments, the inlet 161 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 166 to receive all or a portion of the bottom 174 .

Steam pyrolysis reaction zone 160 has a wide temperature range of 400° C. to 900° C., but preferred operating ranges are 800° C. to 900° C. in the convection section and pyrolysis section; a pressure in the convection section ranging from 1 bar to 3 bar and a pressure in the pyrolysis section ranging from 1 bar to 3 bar; steam-to-hydrocarbon ratio in the convection section ranging from 0.3:1 to 2:1; and residence times in the convection section and in the pyrolysis section ranging from 0.05 seconds to 2 seconds.

Fractionation zone 170 includes an inlet 171 in fluid communication with a steam pyrolysis reaction zone effluent outlet 184 , a product stream outlet 172 and a bottom stream outlet 174 . Note that although one product outlet is shown, multiple product fractions may also be withdrawn from fractionation zone 170 .

The feedstock is introduced through the inlet 102 of the aromatic extraction zone 140 for extraction of the hydrogen-lean fraction and the hydrogen-rich fraction. Optionally, the feedstock may be combined with all or part of the bottom 174 from fractionation zone 170 via recirculation conduit 120 .

The hydrogen-lean fraction 104 generally comprises a majority of the aromatic nitrogen- and sulfur-containing compounds present in the initial feedstock and a small proportion of the non-aromatics present in the initial feedstock. Aromatic nitrogen-containing compounds extracted with the hydrogen-lean fraction include pyrrole, quinoline, acridine, carbazole and derivatives thereof. Aromatic sulfur-containing compounds extracted with the hydrogen-lean fraction include thiophene, benzothiophene and long chain alkylated derivatives thereof, and alkyl derivatives thereof such as dibenzothiophene and 4,6-dimethyl-dibenzothiophene. . The hydrogen-rich fraction generally comprises a majority of the non-aromatic compounds present in the initial feedstock and a small proportion of the aromatic nitrogen- and sulfur-containing compounds present in the initial feedstock. The hydrogen-rich fraction contains few refractory nitrogen-containing compounds and the hydrogen-lean fraction contains nitrogen-containing aromatic compounds.

The hydrogen-lean fraction withdrawn through outlet 104 passes through inlet 151 of first stage hydrocracking reaction zone 150 and is mixed with hydrogen gas through conduit 152 . Optionally, the hydrogen-lean fraction is combined with all or part of the bottom 174 from fractionation zone 170 via recycle conduit 156 . Compounds contained in the hydrogen-lean fraction, including aromatics, are hydrotreated and/or hydrocracked. The first stage hydrocracking reaction zone 150 is operated under relatively harsh conditions. In certain embodiments, the operating conditions in the first stage hydrocracking reaction zone 150 are relatively harsher than commonly known harsh hydrocracking conditions due to the relatively higher concentrations of aromatic nitrogen- and sulfur-containing compounds. However, these harsher conditions capital equipment and operating costs result in the hydrogen-lean feed processed in the first stage hydrocracking reaction zone 150 compared to the full range feed processed in traditional harsh hydrocracking unit operations of the prior art. is offset by the reduced volume of

The hydrocracking reaction zone liquid effluent withdrawn after gas-liquid separation (not shown) via outlet 154 is mixed with the hydrogen-rich fraction withdrawn via outlet 106, It is passed through the inlet 161 . Compounds contained in the mixture of the hydrocracking reaction zone effluent and the hydrogen-rich fraction, including paraffins and naphthenes, are cracked. Optionally, the mixture is combined with the recirculated bottom from fractionation zone 170 introduced via conduit 166 and the flow is controlled by a three-way valve.

A steam pyrolysis reaction zone effluent is more than one intermediate separator vessel (shown in order to remove and recover the gas containing an excess of H _2, H ₂ S, NH _3, methane, ethane, ethylene, propane, propylene, butane and butylene not sent). The liquid effluent is passed through outlet 172 to inlet 171 of fractionation zone 170 for recovery of liquid product, eg, naphtha boiling in a nominal range of about 36° C. to 180° C. and about 180° C. Diesel boiling in the nominal range of to 370°C. The bottom stream exiting outlet 174 comprises, for example, unconverted hydrocarbons and/or partially cracked hydrocarbons having a boiling point greater than about 370°C. The product cut points between fractions are representative only, and in practice the cut points are selected based on the fractionator design characteristics and the composition of the particular feedstock. For example, the value of the cut point can vary up to about 30° C. in the embodiments described herein. Also, although the integrated system is shown and described with one fractionation zone 170 , it should be understood that in certain implementations separate fractionation zones may be effectively used.

All or part of the bottom may be purged via conduit 175, for example, for processing in other unit operations or refineries. In certain embodiments, to maximize yield and conversion, a portion of bottom 174 is, exemplarily indicated by dashed lines 120, 156 and 166, respectively, aromatic separation unit 140, first stage hydrocracking reaction zone. It is recirculated in the process to 150 and its disposition is controlled by three-way valves 177, 167 and 157.

Referring to Figure 4. The process flow diagram illustrates an integrated hydrocracking unit 400 as a configuration of a two-stage hydrocracking unit apparatus and system. The system 400 comprises an aromatic extraction zone 140, a first vessel 150 of a first stage hydrocracking reaction zone containing a first stage hydrocracking catalyst, a steam pyrolysis vessel 160, a second stage hydrocracking catalyst. a second stage hydrocracking reaction zone 180 and a fractionation zone 170 containing

Aromatics extraction zone 140 includes a feed inlet 102 , a hydrogen-lean stream outlet 104 , and a hydrogen-rich stream outlet 106 . In certain embodiments, the feed inlet 102 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 120 to receive all or a portion of the bottom 174 . The unit-operations and/or various embodiments contained within the aromatics separation zone 140 are used in accordance with the prior art based on the nature of the aromatics present in the initial feedstock.

The first vessel 150 of the first stage hydrocracking reaction zone generally includes a hydrogen-lean stream outlet 104 and an inlet 151 in fluid communication with a source of hydrogen gas introduced via conduit 152 . The first vessel 150 of the first stage hydrocracking reaction zone also includes a first vessel first stage hydrocracking reaction zone outlet 154 . In certain embodiments, the inlet 151 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 156 to receive all or a portion of the bottom 174 .

The first vessel 150 of the first stage hydrocracking reaction zone is operated under harsh conditions. As used herein, “severe conditions” are relative and the range of operating conditions depends on the feedstock being treated. In certain embodiments of the processes described herein, these conditions include a reaction temperature ranging from about 300°C to 500°C, and in certain embodiments from about 380°C to 450°C; a reaction pressure ranging from about 100 bar to 200 bar, and in certain embodiments from about 130 bar to 180 bar; a hydrogen feed rate of less than about 2,500 standard liters per liter of hydrocarbon feed (SLt/Lt), in certain embodiments from about 500 to 2,500 SLt/Lt, and in further embodiments from about 1,000 to 1,500 SLt/Lt; and feed rates ranging from about 0.25 h ^-1 to 3.0 ^-1 , and in certain embodiments from about 0.5 ^-1 to 1.0 ^{-1 .}

The catalyst used in the first vessel 150 has one or more active metal components selected from IUPAC Groups 6-10 of the Periodic Table of Elements. In certain embodiments, the active metal component is typically one or more of cobalt, nickel, tungsten and molybdenum deposited or otherwise incorporated on a support such as alumina, silica-alumina, silica or zeolite.

Steam pyrolysis vessel 160 includes a hydrogen-rich stream outlet 106 and an inlet 161 in fluid communication with steam introduced via conduit 162 . Steam pyrolysis vessel 160 includes a steam cracked hydrocarbon reaction zone effluent outlet 164 in fluid communication with an inlet 171 of fractionation zone 170 .

Steam pyrolysis reaction zone 160 has a wide temperature range of 400° C. to 900° C., but a preferred operating range is 800° C. to 900° C. in the convection section and in the pyrolysis section; a pressure in the convection section in the range from 1 bar to 3 bar, and a pressure in the pyrolysis section in the range from 1 bar to 3 bar; steam-to-hydrocarbon ratio in the convection section ranging from 0.3:1 to 2:1; and residence times in the convection section and in the pyrolysis section ranging from 0.05 seconds to 2 seconds.

Fractionation zone 170 includes an inlet 171 in fluid communication with a first stage hydrocracking reaction zone effluent outlet 154 and a steam pyrolysis reaction zone effluent outlet 164 . Fractionation zone 170 also includes a product stream outlet 172 and a bottom stream outlet 174 . As noted above, fractionation zone 170 advantageously includes a plurality of fractionators for receiving and efficiently separating the hydrocracked and hydrotreated streams.

The second stage hydrocracking reaction zone 180 includes a fractionation zone bottom stream outlet 174 and an inlet 181 in fluid communication with a source of hydrogen gas introduced via conduit 182 . Second stage hydrocracking reaction zone 180 also includes a second stage hydrocracking reaction zone outlet 184 in fluid communication with inlet 171 of fractionation zone 170 . It is noted that although one product outlet 172 is shown, multiple product fractions may also be withdrawn from fractionation zone 170 .

The second stage hydrocracking reaction zone 180 is operated under mild conditions. As used herein, "mild conditions" are relative and it will be understood that the range of operating conditions will depend on the feedstock being treated. In certain embodiments of the processes described herein, these conditions include a reaction temperature ranging from about 300° C. to 500° C., and in certain embodiments from about 330° C. to 420° C.; a reaction pressure ranging from about 30 bar to 130 bar, and in certain embodiments from 60 bar to 100 bar; a hydrogen feed rate of less than 2,500 SLt/Lt, and in certain embodiments from about 500 to 2,500 SLt/Lt, and in further embodiments from about 1,000 to 1,500 SLt/Lt; and feed rates ranging from about 1.0 h ⁻¹ to 5.0 h ⁻¹ , and in certain embodiments from about 2.0 h ⁻¹ to 3.0 h ^{−1 .}

The catalyst used in the second stage hydrocracking reaction zone has at least one active metal component selected from IUPAC groups 6-10 of the Periodic Table of the Elements. In certain embodiments, the active metal component is one or more of cobalt, nickel, tungsten, and molybdenum, typically deposited or otherwise incorporated on a support such as alumina, silica-alumina, silica, or zeolite.

The hydrocarbon feedstock is introduced via inlet 102 of aromatic extraction zone 140 for extraction of hydrogen-lean fractions and hydrogen-rich fractions. Optionally, the feedstock may be combined with all or a portion of the bottom 174 from the fractionation zone 170 via a recirculation conduit 120 .

The hydrogen-lean fraction generally comprises a majority of the aromatic nitrogen- and sulfur-containing compounds present in the initial feedstock and a small fraction of the non-aromatics present in the initial feedstock. Aromatic nitrogen-containing compounds extracted with the hydrogen-lean fraction include pyrrole, quinoline, acridine, carbazole and derivatives thereof. Aromatic sulfur-containing compounds extracted with the hydrogen-lean fraction include thiophene, benzothiophene and long chain alkylated derivatives thereof, and alkyl derivatives thereof such as dibenzothiophene and 4,6-dimethyl-dibenzothiophene. . The hydrogen-rich fraction generally comprises a majority of the non-aromatic compounds present in the initial feedstock and a small proportion of the aromatic nitrogen- and sulfur-containing compounds present in the initial feedstock. The hydrogen-rich fraction contains few refractory nitrogen-containing compounds and the hydrogen-lean fraction contains nitrogen-containing aromatic compounds.

The hydrogen-lean fraction withdrawn via outlet 104 is passed to inlet 151 of first vessel 150 of first stage hydrocracking reaction zone and mixed with hydrogen gas via conduit 152 . Optionally, the hydrogen-lean fraction is combined with all or part of the bottom 174 from fractionation zone 170 via recycle conduit 156 . Compounds contained in the hydrogen-lean fraction, including aromatics, are hydrotreated and/or hydrocracked. The first vessel 150 of the first stage hydrocracking reaction zone is operated under relatively harsh conditions. In certain embodiments, these relatively harsh conditions of the first vessel 150 are relatively harsher than conventional harsh hydrocracking conditions due to the relatively higher concentrations of aromatic nitrogen- and sulfur-containing compounds. However, the capital and operating costs of these harsher conditions are at a reduced volume of hydrogen-lean feed processed in the first vessel 150 compared to the full range feed to be processed in conventionally known harsh hydrocracking unit operations. is offset by

The hydrogen-rich fraction discharged through the outlet 106 is passed to the inlet 161 of the steam pyrolysis vessel 160 and mixed with the steam introduced through the conduit 162 . Compounds contained in the hydrogen-rich fraction comprising paraffins and naphthenes are decomposed.

The first vessel first stage hydrocracking reaction zone effluent 154 and steam pyrolysis reaction zone effluent 164 contain excess H ₂ , H ₂ S, NH ₃ , methane, ethane, ethylene, propane, propylene, butane and It is sent to one or more intermediate separator vessels (not shown) to remove butylene. The liquid effluent is passed through outlet 172 to an inlet 171 of fractionation zone 170 for recovery of liquid product, eg, naphtha boiling in a nominal range of about 36° C. to 180° C. and about 180° C. Diesel boiling in the nominal range of to 370°C. It should be understood that the product cut points between fractions are representative only and that in practice the cut points are selected based on design characteristics and considerations for a particular feedstock. For example, the value of the cut point can vary up to about 30° C. in the embodiments described herein. Also, although the integrated system is shown and described as having one fractionation zone 170, it should be understood that in certain embodiments a separate fractionation zone may be effective to recover a product stream having a narrow range of characteristics.

All or a portion of the fractionator bottom 174 may be purged via conduit 175 for, for example, other unit operations or processing at a refinery. In certain embodiments, to maximize yield and conversion, a portion of the bottom 174 is transferred within the process to the aromatic separation unit 140 and/or to the first vessel 150 of the first stage hydrocracking reaction zone 150 . , and/or to the steam pyrolysis vessel 160 , as indicated by dashed lines 120 , 156 and 166 , respectively.

All or a portion of the fractionation zone bottom stream exiting via conduit 174 is mixed with hydrogen gas via inlet 182 and passed to inlet 181 of second stage hydrocracking reaction zone 180 . The second stage hydrocracking reaction zone effluent exits via outlet 184 and is treated in fractionation zone 170 .

The second stage hydrocracking reaction zone 180 operates under relatively mild conditions, which are milder than conventional mild hydrocracking conditions due to the relatively lower concentrations of aromatic nitrogen- and sulfur-containing compounds, resulting in lower capital and operating costs. can save

Referring now to the process flow diagram of FIG. 5 , an integrated hydrocracking apparatus and system 500 is shown as a configuration of a two-stage hydrocracking/steam pyrolysis unit system. The system 500 includes an aromatic extraction zone 140 , a first stage hydrocracking reaction zone 150 containing the first stage hydrocracking catalyst, a steam pyrolysis reaction zone 160 , and a fractionation zone 170 .

Aromatics extraction zone 140 includes a feed inlet 102 , a hydrogen-lean stream outlet 104 , and a hydrogen-rich stream outlet 106 . In certain embodiments, the feed inlet 102 is in fluid communication with the fractionation zone 170 via an optional recirculation conduit 120 to receive all or a portion of the bottom stream 174 . A variety of prior art embodiments and unit-operations included in the aromatics extraction zone 140 may be used, the selection of which is within the skill of the art and is based, inter alia, on the nature of the aromatics of the initial feed.

The first stage hydrocracking reaction zone 150 has a hydrogen-lean stream outlet 104 , an inlet 151 in fluid communication with a source of hydrogen gas introduced via conduit 152 , and a first stage hydrocracking reaction zone outlet and a water outlet 154 . In certain embodiments, the inlet 151 is in fluid communication with the fractionation section 170 via an optional recirculation conduit 156 to receive all or a portion of the bottom 174, the flow being intermediate three-way as described above. controlled by a valve.

The first stage hydrocracking reaction zone 150 is operated under harsh conditions. As used herein, “severe conditions” are relative and the range of operating conditions depends on the feedstock being processed. In certain embodiments of the processes described herein, such conditions include a reaction temperature ranging from about 300°C to 500°C, and in certain embodiments from about 380°C to 450°C; a reaction pressure ranging from about 100 bar to 200 bar, and in certain embodiments from about 130 bar to 180 bar; a hydrogen feed rate of not more than about 2,500 standard liters per liter of hydrocarbon feed (SLt/Lt), and in certain embodiments from about 500 to 2,500 SLt/Lt, and in further embodiments from 1,000 to 1,500 SLt/Lt; and feed rates ranging from about 025 h ⁻¹ to 3.0 h ⁻¹ , and in certain embodiments from about 0.5 h ⁻¹ to 1.0 h ^{−1 .}

The catalyst used in the first stage hydrocracking reaction zone has at least one active metal component selected from IUPAC groups 6-10 of the Periodic Table of the Elements. In certain embodiments, the active metal component is one or more of cobalt, nickel, tungsten, and molybdenum, typically deposited or otherwise incorporated on a support such as alumina, silica-alumina, silica, or zeolite.

Fractionation zone 170 has an inlet 171 in fluid communication with a first stage hydrocracking reaction zone effluent outlet 154 and a second stage hydrocracking reaction zone effluent outlet 184, a product stream outlet 172 and a bottom and a stream outlet 174 . Although one product outlet is shown for convenience, in practice multiple product fractions will be withdrawn from multiple fractionators operating in fractionation zone 170 .

Steam pyrolysis reaction zone 160 includes a hydrogen-rich stream outlet 106 , a fractionation zone bottom stream outlet 174 , and an inlet 161 in fluid communication with steam via conduit 162 . Steam pyrolysis reaction zone 160 also includes a steam pyrolysis reaction zone effluent outlet 164 in fluid communication with inlet 171 of fractionation zone 170 .

The hydrocarbon feedstock is introduced via inlet 102 of aromatic extraction zone 140 for extraction of hydrogen-lean fractions and hydrogen-rich fractions. Optionally, the feedstock may be combined with all or a portion of the bottom 174 from the fractionation zone 170 via recirculation conduit 120 , the flow of which is controlled by three-way valves 177 and 157 .

The hydrogen-lean fraction generally comprises a majority of the aromatic nitrogen- and sulfur-containing compounds present in the initial feedstock and a small fraction of the non-aromatics present in the initial feedstock. Aromatic nitrogen-containing compounds extracted with the hydrogen-lean fraction include pyrrole, quinoline, acridine, carbazole and derivatives thereof. Aromatic sulfur-containing compounds extracted with the hydrogen-lean fraction include thiophene, benzothiophene and long chain alkylated derivatives thereof, and alkyl derivatives thereof such as dibenzothiophene and 4,6-dimethyl-dibenzothiophene. . The hydrogen-rich fraction generally comprises a majority of the non-aromatic compounds initially present in the feedstock and a small proportion of the aromatic nitrogen- and sulfur-containing compounds initially present in the feedstock. The hydrogen-rich fraction contains few refractory nitrogen-containing compounds and the hydrogen-lean fraction contains nitrogen-containing aromatic compounds.

The first stage hydrocracking reaction zone 150 is operated under relatively harsh conditions. In certain embodiments, these relatively harsh conditions of first step 150 are more severe than conventional harsh hydrocracking conditions due to the relatively higher concentrations of aromatic nitrogen- and sulfur-containing compounds. However, these harsher conditions capital equipment and operating costs result from the reduced hydrogen-lean feed processed in the first stage 150 compared to the full range feed processed in the existing harsh hydrocracking unit operation of the prior art. offset by volume.

The hydrogen-lean fraction withdrawn via outlet 104 is passed to inlet 151 of first stage hydrocracking reaction zone 150 and mixed with hydrogen gas introduced via conduit 152 . Optionally, the hydrogen-lean fraction is combined with all or part of the bottom 174 from fractionation zone 170 via recycle conduit 156 . Compounds contained in the hydrogen-lean fraction comprising aromatic compounds are hydrotreated and/or hydrocracked.

The first stage hydrocracking reaction zone effluent is sent to one or more intermediate separator vessels (not shown) to remove gases comprising _{excess H 2} , H ₂ S, NH _{3 , methane, ethane, propane and butane.} . The liquid effluent passes through outlet 172 for recovery of gaseous and liquid products comprising, for example, naphtha nominally boiling in the range of about 36°C to 180°C and diesel nominally boiling in the range of about 180°C to 370°C. It is passed to the inlet 171 of the fractionation section 170 for the hazard. The bottom stream exiting through outlet 174 comprises unconverted hydrocarbons and/or partially cracked hydrocarbons having, for example, a boiling point greater than about 370°C. The product cut points between fractions are representative only, and in practice the cut points are selected based on classifier design parameters and specific feedstock properties. For example, the value of the cut point can vary up to about 30° C. in the embodiments described herein. Also, although an integrated system is shown and described with one fractionation zone 170, it should be understood that in certain embodiments a separate fractionation zone may be effectively used to enhance recovery of certain fractions.

All or part of the bottom may be purged through conduit 175, for example, for processing in other unit operations or refineries. In certain embodiments, to maximize yield and conversion, a portion of bottom 174 may be separated from aromatic extraction zone 140 and/or first stage hydrocracking reaction zone 150, as indicated by dashed lines 120 and 156, respectively. ) is recycled.

A mixture of all or a portion of the fractionation zone bottom stream exiting via conduit 174, the hydrogen-rich fraction exiting via outlet 106 and steam introduced via conduit 162 is It is passed through the inlet 161 . The steam pyrolysis reaction zone effluent exits via outlet 164 and is treated in fractionation zone 170 . Compounds contained in the mixture of the first stage hydrocracking reaction zone bottom and the hydrogen-rich fraction comprising paraffins and naphthenes are hydrotreated and/or hydrocracked. Steam cracking reaction zone 160 has a wide temperature range of 400° C. to 900° C., but the preferred operating range is 800° C. to 900° C. in the convection section and pyrolysis section; steam-to-hydrocarbon ratio in the convection section ranging from 0.3:1 to 2:1; and residence times in the convection section and the pyrolysis section in the range of 0.05 seconds to 2 seconds.

Additionally, one or both of the hydrogen-rich fraction and the hydrogen-lean fraction may also include residual extraction solvent from the aromatic extraction zone 140 . In certain embodiments, the extraction solvent may be recovered and recycled as product via fractionator outlet 172 .

In the foregoing embodiments, suitable feedstocks may include any liquid hydrocarbon feeds commonly recognized by those skilled in the art as suitable for hydrocracking operations. For example, a typical hydrocracking feedstock is vacuum gas oil (VGO) boiling in a nominal range of about 300°C to 900°C and in certain embodiments in a range of about 370°C to 520°C. Demetallic oil (DMO) or deasphalted oil (DAO) can be used alone or mixed with VGO. Hydrocarbon feedstocks can be derived from naturally occurring fossil fuels such as crude oil, shale oil or coal liquid; or intermediate refinery products or distillate fractions thereof, such as naphtha, gas oil, coker liquid, fluid catalytic cracking cycle oil, resid, or a combination of any of the foregoing sources. Generally, the aromatic content in the VGO feedstock ranges from about 15 to 60% by volume (V%). The recycle stream comprises 0 W% to about 80 W% of stream 174, and in certain embodiments about 10 W% to 70 W% of stream 174, and in further embodiments about 20 W% of stream 174. to 60 W%, for example, from about 10 W% to 80 W%, based on conversion in each zone.

Aromatics separation devices may be based on selective aromatics extraction. For example, the aromatics separation unit may be a suitable aromatic solvent extraction separation unit capable of splitting the feed into a generally hydrogen-rich stream and generally a hydrogen-lean stream. Systems comprising a variety of established aromatics extraction processes and unit operations used at different stages of various refineries and other petroleum-related operations can advantageously be used as aromatic separation units in the present process. In certain existing processes, it is desirable to remove aromatics from end products such as lubricating oils and certain fuels such as diesel fuel. In other processes, aromatics are extracted to produce hydrogen-lean products for use in various chemical processes and as octane boosters for gasoline.

The process and system of the present invention have been described in detail above and by way of the accompanying schematics and examples. Various modifications will be apparent to those skilled in the art from this description, and the scope of protection for the present invention will be determined by the following claims.

Claims (15)

An integrated hydrocracking and steam pyrolysis process for producing cracked hydrocarbons from a hydrocarbon feed containing aromatic, paraffinic and olefinic compounds, the process comprising:
introducing a hydrocarbon feed to an aromatics separation zone and recovering an aromatics-rich fraction and an aromatics-lean fraction from the aromatics separation zone;
b. Reaction temperature in the range of 300° C. to 500° C., reaction pressure in the range of 130 bar to 200 bar, hydrogen feed rate of standard liters per liter of hydrocarbon feed (SLt/Lt) up to 2500, and range of ^{0.25 h -1} to 3.0 h ^-1 hydrocracking the aromatics-rich fraction in a hydrocracking reaction zone at a feed rate of to produce a hydrocracking reaction zone effluent;
c. Temperature in the range from 400° C. to 900° C. in the convection section and in the pyrolysis section, pressure in the convection section in the range from 1 bar to 3 bar, and pressure in the pyrolysis section in the range from 1 bar to 3 bar, 0.3:1 to 2: Aromatic-lean for cracking by steam pyrolysis in a steam pyrolysis reaction zone operating at a steam-to-hydrocarbon ratio in the convection section in the range of 1, and a combined residence time in the convection and pyrolysis sections in the range of 0.05 seconds to 2 seconds. applying fractions to produce a cracked steam pyrolysis reaction zone effluent comprising light olefins, gases and pyrolysis oils; and
d. An integrated hydrocracking and steam pyrolysis process comprising fractionating, in a fractionation zone, a hydrocracking reaction zone effluent and a steam pyrolysis reaction zone effluent to produce at least one product stream and at least one bottom stream. The method according to claim 1,
An integrated hydrocracking and steam pyrolysis process, wherein all or a portion of the one or more fractionation zone bottom streams are selectively passed to one or more of a steam pyrolysis reaction zone, a hydrocracking reaction zone and an aromatics extraction zone for further processing. The method according to claim 1,
wherein the hydrocracking reaction zone is operated under relatively harsh conditions effective to hydrocrack at least a portion of the aromatics contained in the aromatics-rich fraction and remove heteroatoms therefrom. The method according to claim 1,
wherein the aromatics-rich fraction comprises nitrogen-containing aromatics including pyrrole, quinoline, acridine, carbazole, and derivatives thereof. The method according to claim 1,
wherein the aromatics-rich fraction comprises thiophene, benzothiophene and derivatives thereof, and aromatic sulfur compounds including dibenzothiophene and derivatives thereof. The method according to claim 1,
Separating the hydrocarbon feed into an aromatics-lean fraction and an aromatics-rich fraction include:
passing a hydrocarbon feed and an effective amount of extraction solvent to an extraction zone, and a solvent extract containing a majority of the aromatic content of the hydrocarbon feed and a portion of the extraction solvent, and a majority of the non-aromatic content of the hydrocarbon feed and a portion of the extraction solvent recovering the raffinate containing;
separating at least a substantial portion of the extraction solvent from the raffinate and maintaining an aromatics-lean fraction; and
An integrated hydrocracking and steam pyrolysis process comprising separating at least a substantial portion of the extraction solvent from the solvent extract and maintaining an aromatics-rich fraction. The method according to claim 1,
The steam pyrolysis reaction zone has a temperature in the range of 825° C. to 875° C. in the convection section and in the pyrolysis section, a steam-to-hydrocarbon ratio in the convection section in the range of 0.3:1 to 2:1; a pressure of 1 to 2 bar in the pyrolysis section; An integrated hydrocracking and steam pyrolysis process, operated at residence times in the pyrolysis section and in the convection section in the range from 0.05 seconds to 2 seconds. An integrated hydrocracking and steam pyrolysis process for producing transport fuel blending components and light olefins from hydrocarbon feeds containing aromatic, paraffinic and olefinic compounds, the process comprising:
a. in an aromatics extraction zone, separating the hydrocarbon feed into a hydrogen-rich fraction comprising paraffins and olefin compounds and a hydrogen-lean fraction comprising aromatic compounds;
b. introducing the hydrogen-lean fraction to a hydrocracking reaction zone comprising a first stage hydrocracking reaction vessel at a reaction pressure in the range of 130 bar to 200 bar to produce a first stage hydrocracking reaction zone effluent;
c. The hydrogen-rich fraction is subjected to a temperature ranging from 800° C. to 900° C. in a convection section and a pyrolysis section, a pressure in the convection section ranging from 1 bar to 3 bar, a pressure in the pyrolysis section ranging from 1 bar to 3 bar, 0.3 Steam pyrolysis in a steam pyrolysis reaction zone, operating at a steam-to-hydrocarbon ratio in the convection section ranging from :1 to 2:1, and a combined residence time in the convection section and pyrolysis section ranging from 0.05 seconds to 2 seconds. producing a steam cracked pyrolysis reaction zone effluent;
d. hydrocracking the first stage hydrocracking reaction zone effluent in a second stage hydrocracking reaction zone to produce a second stage hydrocracking reaction zone effluent; and
e. An integrated hydrocracking and steam pyrolysis process comprising fractionating a combined second stage hydrocracking reaction zone effluent and a steam cracked reaction zone effluent to produce at least one product stream and at least one bottom stream. 9. The method of claim 8,
An integrated hydrocracking and steam pyrolysis process, wherein all or a portion of the one or more fractionation zone bottom streams are optionally passed to a second stage hydrocracking zone, a first stage hydrocracking zone and an aromatics extraction zone for further processing. An integrated hydrocracking and steam pyrolysis process for producing cracked hydrocarbons from a hydrogen feed containing aromatic, paraffinic and olefinic compounds, the process comprising:
a. in an aromatics extraction zone, separating the hydrocarbon feed into a hydrogen-rich fraction comprising paraffins and olefin compounds and a hydrogen-lean fraction comprising aromatic compounds;
b. hydrocracking the hydrogen-lean fraction in a first stage hydrocracking reaction zone to produce a first stage hydrocracking reaction zone effluent;
c. subjecting the first stage hydrocracking reaction zone effluent to a gas-liquid separation stage, and passing the separated liquid and hydrogen-rich fractions to a steam pyrolysis reaction zone to produce a cracked steam pyrolysis reaction zone effluent; and
d. passing the cracked steam pyrolysis reaction zone effluent to a fractionation zone, and fractionating the steam pyrolysis reaction zone effluent, and recovering at least one low molecular weight product stream and at least one bottom stream. Integrated hydrocracking and steam pyrolysis processes. 11. The method of claim 10,
An integrated hydrocracking and steam pyrolysis process, wherein all or a portion of the one or more fractionation zone bottom streams are optionally passed to a steam pyrolysis zone, a first stage hydrocracking zone and an aromatics extraction zone for further processing. An integrated hydrocracking and steam pyrolysis process for producing cracked hydrocarbons from a feed containing aromatic, paraffin and olefinic compounds, the process comprising:
a. separating the hydrocarbon feed into a hydrogen-rich fraction comprising paraffins and olefin compounds and a hydrogen-lean fraction comprising aromatic compounds;
b. hydrocracking the hydrogen-lean fraction in a first stage hydrocracking reaction zone to produce a first stage hydrocracking reaction zone effluent;
c. subjecting the hydrogen-rich fraction to steam pyrolysis in a steam pyrolysis reaction zone to produce a steam cracked hydrocarbon effluent;
d. fractionating a mixture comprising a first stage hydrocracking reaction zone effluent and a steam cracked hydrocarbon effluent in a fractionation zone to produce one or more fractionation zone product streams and one or more fractionation zone bottom streams;
e. passing at least a portion of the one or more fractionation zone bottom streams to a second stage hydrocracking reaction zone to produce a second stage hydrocracking reaction zone effluent; and
f. passing the second stage hydrocracking reaction zone effluent to a fractionation zone for fractionation into a first stage hydrocracking reaction zone effluent and a steam cracked hydrocarbon effluent to produce at least one product stream and at least one bottom stream , an integrated hydrocracking and steam pyrolysis process. 13. The method of claim 12,
An integrated hydrocracking and steam pyrolysis process, wherein all or a portion of the one or more fractionation zone bottom streams are optionally passed to a first stage hydrocracking zone, an aromatics extraction zone and a steam pyrolysis zone for further processing. An integrated hydrocracking process for producing cracked hydrocarbons from a hydrocarbon feed containing aromatic, paraffinic and olefinic compounds, the process comprising:
a. in an aromatics separation zone, separating the hydrocarbon feed into a hydrogen-rich fraction comprising paraffins and olefin compounds and a hydrogen-lean fraction comprising aromatic compounds;
b. hydrocracking the hydrogen-lean fraction in a first stage hydrocracking reaction zone to produce a first stage hydrocracking reaction zone effluent;
c. fractionating the first stage hydrocracking reaction zone effluent into an effluent from a downstream steam pyrolysis reaction zone in a fractionation zone to produce at least one fractionation zone product stream and at least one fractionation zone bottom stream;
d. subjecting at least a portion of the one or more fractionation zone bottom streams and a mixture of the hydrogen-rich fractions to steam pyrolysis in a steam pyrolysis reaction zone to produce a steam cracked hydrocarbon effluent; and
e. and passing the steam cracked hydrocarbon effluent to a fractionation zone for fractionation into a first stage hydrocracking zone effluent to produce at least one product stream and at least one bottom stream. 15. The method of claim 14,
wherein all or a portion of the at least one fractionation zone bottom stream is optionally passed to a first stage hydrocracking zone and an aromatics extraction zone for further processing.

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